472 



D. O. JORDAN 



1 — 1 — \ — r 



Oi 0-2 0-3 0-4 OS 0-6 



Conc«ntrotlon per cent 



Fig. 13. Variation of 1/S with concentration (Kahler*^). 



Fig. 14. Diffusion of 0.9% sodium deoxypentose nucleate in buffer at pH 7.4 

 and 20° in normal coordinates (O). Ideal normal curve (•) (Kahler^^). 



tained by Ogston*^ was between 0.55 and 0.70 X 10~^ and that found by 

 Kahler,^2 0.45 x 10~^ Combination of the sedimentation and diffusion re- 

 sults yield the values 1.3 X lO^.^o^^ 1.5 X 10«,«2 and 1.3 X 10^ ^^ for differ- 

 ent preparations of the sodium deoxyribonucleate of calf thymus. 



In view of the difficulties attendant upon the determination of the 

 of the molecular weights of nucleic acids by sedimentation and diffusion 

 methods, other methods have been used, and probably the most accurate 

 information on the molecular weight and size and shape of the deoxypentose 

 nucleate ion in neutral solution has been obtained by Doty and Bunce^^ 



